A Hub Dynamometer for Measurement of Wheel Forces in Off-Road Bicycling

1999 ◽  
Vol 121 (1) ◽  
pp. 132-137 ◽  
Author(s):  
D. S. De Lorenzo ◽  
M. L. Hull
Keyword(s):  
Measurement Errors ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Front Wheel ◽  
Full Scale ◽  
Contact Forces ◽  
Ground Contact ◽  
Strain Gages ◽  
Accuracy Check ◽  
Force Components

A dynamometric hubset that measures the two ground contact force components acting on a bicycle wheel in the plane of the bicycle during off-road riding while either coasting or braking was designed, constructed, and evaluated. To maintain compatibility with standard mountain bike construction, the hubs use commercially available shells with modified, strain gage-equipped axles. The axle strain gages are sensitive to forces acting in the radial and tangential directions, while minimizing sensitivity to transverse forces, steering moments, and variations in the lateral location of the center of pressure. Static calibration and a subsequent accuracy check that computed differences between applied and apparent loads developed during coasting revealed root mean squared errors of 1 percent full-scale or less (full-scale load = 4500 N). The natural frequency of the rear hub with the wheel attached exceeded 350 Hz. These performance capabilities make the dynamometer useful for its intended purpose during coasting. To demonstrate this usefulness, sample ground contact forces are presented for a subject who coasted downhill over rough terrain. The dynamometric hubset can also be used to determine ground contact forces during braking providing that the brake reaction force components are known. However, compliance of the fork can lead to high cross-sensitivity and corresponding large (>5 percent FS) measurement errors at the front wheel.

scholarly journals Development of a Subject-Specific Foot-Ground Contact Model for Walking

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Jennifer N. Jackson ◽  
Chris J. Hass ◽  
Benjamin J. Fregly
Keyword(s):  
Center Of Pressure ◽  
Reaction Force ◽  
Walking Ability ◽  
Vertical Force ◽  
Ground Contact ◽  
Contact Pattern ◽  
Flexion Extension ◽  
Subject Specific ◽  
Contact Models ◽  
Force Components

Computational walking simulations could facilitate the development of improved treatments for clinical conditions affecting walking ability. Since an effective treatment is likely to change a patient's foot-ground contact pattern and timing, such simulations should ideally utilize deformable foot-ground contact models tailored to the patient's foot anatomy and footwear. However, no study has reported a deformable modeling approach that can reproduce all six ground reaction quantities (expressed as three reaction force components, two center of pressure (CoP) coordinates, and a free reaction moment) for an individual subject during walking. This study proposes such an approach for use in predictive optimizations of walking. To minimize complexity, we modeled each foot as two rigid segments—a hindfoot (HF) segment and a forefoot (FF) segment—connected by a pin joint representing the toes flexion–extension axis. Ground reaction forces (GRFs) and moments acting on each segment were generated by a grid of linear springs with nonlinear damping and Coulomb friction spread across the bottom of each segment. The stiffness and damping of each spring and common friction parameter values for all springs were calibrated for both feet simultaneously via a novel three-stage optimization process that used motion capture and ground reaction data collected from a single walking trial. The sequential three-stage process involved matching (1) the vertical force component, (2) all three force components, and finally (3) all six ground reaction quantities. The calibrated model was tested using four additional walking trials excluded from calibration. With only small changes in input kinematics, the calibrated model reproduced all six ground reaction quantities closely (root mean square (RMS) errors less than 13 N for all three forces, 25 mm for anterior–posterior (AP) CoP, 8 mm for medial–lateral (ML) CoP, and 2 N·m for the free moment) for both feet in all walking trials. The largest errors in AP CoP occurred at the beginning and end of stance phase when the vertical ground reaction force (vGRF) was small. Subject-specific deformable foot-ground contact models created using this approach should enable changes in foot-ground contact pattern to be predicted accurately by gait optimization studies, which may lead to improvements in personalized rehabilitation medicine.

A Pedal Dynamometer for Off-Road Bicycling

1998 ◽  
Vol 120 (1) ◽  
pp. 160-164 ◽  
Author(s):  
T. Rowe ◽  
M. L. Hull ◽  
E. L. Wang
Keyword(s):  
Wheatstone Bridge ◽  
Accuracy Evaluation ◽  
Strain Gages ◽  
Original Design ◽  
Road Cycling ◽  
Accuracy Check ◽  
Force Components ◽  
Bridge Circuits ◽  
Mean Square Errors ◽  
Ergometer Cycling

This paper describes the design and accuracy evaluation of a dynamometric pedal, which measures the two pedal force components in the plane of the bicycle. To realize a design that could be used during actual off-road cycling, a popular clipless pedal available commercially was modified so that both the form and the function of the original design were maintained. To measure the load components of interest, the pedal spindle was replaced with a spindle fixed to the pedal body and instrumented with eight strain gages connected into two Wheatstone bridge circuits. The new spindle is supported by bearings in the crank arm. Static calibration and a subsequent accuracy check revealed root mean square errors of less than 1 percent full scale (FS) when only the force components of interest were applied. Application of unmeasured load components created an error less than 2 percent FS. The natural frequency with half the weight of a 75 kgf person standing on the pedal was greater than 135 Hz. These performance capabilities make the dynamometer suitable for measuring either pedaling loads due to the rider’s muscular action or inertial loads due to surface-induced acceleration. To demonstrate this suitability, sample pedal load data are presented both for steady-state ergometer cycling and coasting over a rough surface while standing.

scholarly journals A computational gait model with a below-knee amputation and a semi-active variable-stiffness foot prosthesis

2021 ◽  
Author(s):  
Michael McGeehan
Keyword(s):  
Lower Limb ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Variable Stiffness ◽  
Contact Forces ◽  
Prosthesis Design ◽  
Limb Loss ◽  
Design Parameters ◽  
Knee Amputation ◽  
Musculoskeletal Models

Introduction: Simulations based on computational musculoskeletal models are powerful tools for evaluating the effects of potential biomechanical interventions, such as implementing a novel prosthesis. However, the utility of simulations to evaluate the effects of varied prosthesis design parameters on gait mechanics has not been fully realized due to lack of a readily-available limb loss-specific gait model and methods for efficiently modeling the energy storage and return dynamics of passive foot prostheses. The purpose of this study was to develop and validate a forward simulation-capable gait model with lower limb loss and a semi-active variable-stiffness foot (VSF) prosthesis. Methods: A seven-segment 28-DoF gait model was developed and forward kinematics simulations, in which experimentally-observed joint kinematics were applied and the resulting contact forces under the prosthesis evolved accordingly, were computed for four subjects with unilateral below-knee amputation walking with a VSF. Results: Model-predicted resultant ground reaction force (GRFR) matched well under trial-specific optimized parameter conditions (mean R2: 0.97, RMSE: 7.7% body weight (BW)) and unoptimized (subject-specific, but not trial-specific) parameter conditions (mean R2: 0.93, RMSE: 12% BW). Simulated anterior-posterior center of pressure demonstrated a mean R2 = 0.64 and RMSE = 14% foot length. Simulated kinematics remained consistent with input data (0.23 deg RMSE, R2 > 0.99) for all conditions. Conclusions: These methods may be useful for simulating gait among individuals with lower limb loss and predicting GRFR arising from gait with novel VSF prostheses. Such data are useful to optimize prosthesis design parameters on a user-specific basis.

Ankle Control in Walking and Running: Speed- and Gait-Related Changes in Dynamic Mean Ankle Moment Arm

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Peter Gabriel Adamczyk
Keyword(s):  
High Speed ◽  
Center Of Pressure ◽  
Human Subjects ◽  
Reaction Force ◽  
Qualitative Change ◽  
Ground Contact ◽  
Moment Arm ◽  
Running Speed ◽  
Ankle Moment ◽  
Quantitative Evidence

Abstract The human foot–ankle complex uses heel-to-toe ground contact progression in walking, but primarily forefoot contact in high-speed running. This qualitative change in ankle control is clear to the runner, but current measures of ankle behavior cannot isolate the effect, and it is unknown how it changes across moderate speeds. We investigated this dynamic ankle control across a range of walking and running speeds using a new measure, the dynamic mean ankle moment arm (DMAMA): the ratio of sagittal ankle moment impulse to ground reaction force impulse on a single limb. We hypothesized that DMAMA would increase with speed in both walking and running, indicating more forefoot-dominated gait with ground reaction forces more anterior to the ankle. Human subjects walked (1.0–2.0 m/s) and ran (2.25–5.25 m/s) on an instrumented treadmill with motion capture and pressure insoles to estimate DMAMA. DMAMA decreased with increasing walking speed, then increased upon the transition to running, and increased further with increasing running speed. These results provide quantitative evidence that walking becomes more hindfoot-dominated as speed increases—similar to behavior during acceleration—and that running is more forefoot-dominated than walking. The instantaneous center of pressure (COP) at initial ground contact did not follow the same trends. The discrepancy highlights the value of DMAMA in summarizing ankle control across the whole stance phase. DMAMA may provide a useful outcome metric for evaluating biomimetic prostheses and for quantifying foot contact styles in running.

scholarly journals A New Method to Prescribe Wedges Custom Made For Individuals With Transfemoral Amputation Using Principal Component Analysis

2017 ◽  
Vol 10 (1) ◽  
pp. 229-238
Author(s):  
Denise Paschoal Soares ◽  
Marcelo Peduzzi de Castro ◽  
Emília Mendes ◽  
Leandro Machado
Keyword(s):  
Principal Component Analysis ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Specific Effect ◽  
Principal Component ◽  
Component Analysis ◽  
Gait Pattern ◽  
Gait Patterns ◽  
Custom Made ◽  
Force Components

Objective: Wedges custom made have been used to improve the gait pattern of individuals with transfemoral (TF) Amputation. However, the prescription and test of these wedges is mostly based on a highly subjective gait evaluation. The purpose of this study was to develop a rational and quantitative method to prescribe wedges custom made for the sound limb of individuals with TF using Principal Component Analysis (PCA). Method: First, the effect of different wedges was assessed in able-bodied subjects (CG). Second, using the influence of the wedges in CG, and the gait pattern of each TF individually, wedges were prescribed in order to modify their gait according to the specific effect of each wedge. The variables analyzed were the ground reaction force components and center of pressure displacement. The Mahalanobis distance for each variable and the 95% confidence interval (CI) based on CG data was calculated. Results showed, by the Mahalanobis distance of the variables, that TF subjects improved their gait pattern, TF subjects improved their gait; the variables that were out of the boundaries of 95% CI of CG, moved inside these boundaries with the use of wedges. Result: The application of wedges to the sound limb of TF amputees can improve their gait patterns, thus the application of PCA can help clinicians to decide the best device for each patient, and consequently improve TF patient quality of life.

scholarly journals A Computational Gait Model with a Below-Knee Amputation and a Semi-Active Variable-Stiffness Foot Prosthesis

2021 ◽  
Author(s):  
Michael McGeehan ◽  
Peter Adamczyk ◽  
Kieran Nichols ◽  
Michael E. Hahn
Keyword(s):  
Lower Limb ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Variable Stiffness ◽  
Contact Forces ◽  
Prosthesis Design ◽  
Limb Loss ◽  
Design Parameters ◽  
Knee Amputation ◽  
Musculoskeletal Models

Abstract Introduction: Simulations based on computational musculoskeletal models are powerful tools for evaluating effects of potential biomechanical interventions, such as implementing a novel prosthesis. However, the utility of simulations to evaluate effects of prosthesis design parameters on gait mechanics has not been fully realized due to lack of a readily-available limb loss-specific gait model and methods for efficiently modeling the energy storage and return dynamics of passive foot prostheses. The purpose of this study was to develop and validate a forward simulation-capable gait model with lower limb loss and a semi-active variable-stiffness foot (VSF) prosthesis. Methods: A seven-segment 28-DoF gait model was developed and forward kinematics simulations, in which experimentally-observed joint kinematics were applied and resulting foot contact forces evolved accordingly, were computed for four subjects with unilateral below-knee amputation walking with a VSF. Results: Model-predicted resultant ground reaction force (GRFR) matched well under trial-specific optimized parameter conditions (mean R2: 0.97, RMSE: 7.7% body weight (BW)) and unoptimized (subject-specific, not trial-specific) parameter conditions (mean R2: 0.93, RMSE: 12% BW). Simulated anterior-posterior center of pressure demonstrated mean R2 = 0.64 and RMSE = 14% foot length. Simulated kinematics remained consistent with input data (0.23 deg RMSE, R2 > 0.99) for all conditions. Conclusions: These methods may be useful for simulating gait of individuals with lower limb loss and predicting GRFR with novel VSF prostheses. Such data are useful to optimize user-specific prosthesis design parameters.

scholarly journals The Design and Simulation of a 16-Sensors Plantar Pressure Insole Layout for Different Applications: From Sports to Clinics, a Pilot Study

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1450
Author(s):  
Alfredo Ciniglio ◽  
Annamaria Guiotto ◽  
Fabiola Spolaor ◽  
Zimi Sawacha
Keyword(s):  
Pressure Distribution ◽  
Plantar Pressure ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Weight Lifting ◽  
Lower Limbs ◽  
Plantar Pressure Distribution ◽  
Drop Landing ◽  
Mean Pressure ◽  
Footwear Design

The quantification of plantar pressure distribution is widely done in the diagnosis of lower limbs deformities, gait analysis, footwear design, and sport applications. To date, a number of pressure insole layouts have been proposed, with different configurations according to their applications. The goal of this study is to assess the validity of a 16-sensors (1.5 × 1.5 cm) pressure insole to detect plantar pressure distribution during different tasks in the clinic and sport domains. The data of 39 healthy adults, acquired with a Pedar-X® system (Novel GmbH, Munich, Germany) during walking, weight lifting, and drop landing, were used to simulate the insole. The sensors were distributed by considering the location of the peak pressure on all trials: 4 on the hindfoot, 3 on the midfoot, and 9 on the forefoot. The following variables were computed with both systems and compared by estimating the Root Mean Square Error (RMSE): Peak/Mean Pressure, Ground Reaction Force (GRF), Center of Pressure (COP), the distance between COP and the origin, the Contact Area. The lowest (0.61%) and highest (82.4%) RMSE values were detected during gait on the medial-lateral COP and the GRF, respectively. This approach could be used for testing different layouts on various applications prior to production.

Biomechanics Differ for Individuals With Similar Self-Reported Characteristics of Patellofemoral Pain During a High-Demand Multiplanar Movement Task

2020 ◽  
pp. 1-10
Author(s):  
Matthew K. Seeley ◽  
Seong Jun Son ◽  
Hyunsoo Kim ◽  
J. Ty Hopkins
Keyword(s):  
Ground Reaction Force ◽  
Injury Risk ◽  
Reaction Force ◽  
Patellofemoral Pain ◽  
Joint Torque ◽  
Whole Body ◽  
Ground Contact ◽  
High Demand ◽  
Contact Phase ◽  
Hip Extension

Context: Patellofemoral pain (PFP) is often categorized by researchers and clinicians using subjective self-reported PFP characteristics; however, this practice might mask important differences in movement biomechanics between PFP patients. Objective: To determine whether biomechanical differences exist during a high-demand multiplanar movement task for PFP patients with similar self-reported PFP characteristics but different quadriceps activation levels. Design: Cross-sectional design. Setting: Biomechanics laboratory. Participants: A total of 15 quadriceps deficient and 15 quadriceps functional (QF) PFP patients with similar self-reported PFP characteristics. Intervention: In total, 5 trials of a high-demand multiplanar land, cut, and jump movement task were performed. Main Outcome Measures: Biomechanics were compared at each percentile of the ground contact phase of the movement task (α = .05) between the quadriceps deficient and QF groups. Biomechanical variables included (1) whole-body center of mass, trunk, hip, knee, and ankle kinematics; (2) hip, knee, and ankle kinetics; and (3) ground reaction forces. Results: The QF patients exhibited increased ground reaction force, joint torque, and movement, relative to the quadriceps deficient patients. The QF patients exhibited: (1) up to 90, 60, and 35 N more vertical, posterior, and medial ground reaction force at various times of the ground contact phase; (2) up to 4° more knee flexion during ground contact and up to 4° more plantarflexion and hip extension during the latter parts of ground contact; and (3) up to 26, 21, and 48 N·m more plantarflexion, knee extension, and hip extension torque, respectively, at various times of ground contact. Conclusions: PFP patients with similar self-reported PFP characteristics exhibit different movement biomechanics, and these differences depend upon quadriceps activation levels. These differences are important because movement biomechanics affect injury risk and athletic performance. In addition, these biomechanical differences indicate that different therapeutic interventions may be needed for PFP patients with similar self-reported PFP characteristics.

scholarly journals The Effects of Muscle Energy on Low Back Pain: A 3D Analysis of running biomechanics

2021 ◽  
Vol 9 (1) ◽  
pp. 51
Author(s):  
Alisa Drapeaux ◽  
Jon Hurdelbrink
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Reaction Force ◽  
Low Back ◽  
Ground Contact ◽  
Peak Acceleration ◽  
Clinical Exam ◽  
Ground Contact Time ◽  
Muscle Energy ◽  
Initial Peak

Background: Muscle energy technique (MET) is asn osteopathic treatment technique that is utilized frequently in the clinical setting, yet the overall effectiveness is minimally supported within literature. MET is an osteopathic technique that involves an isometric contract relax technique intended to improve alignment and enhance neuromuscular education. Objective: The purpose of this study was to determine the effectiveness of MET on running kinetics on subjects with low back pain. Method: A quasi-experimental research design was implemented and subjects, all of whom either had a history of or currently experience low back pain, underwent pre-intervention data collection of: anthropometric measurements, medical history, dorsaVi 3D running analysis, and a musculoskeletal and neurological clinical exam. Subjects underwent 6 weeks of isolated lumbo-pelvic MET at a frequency of twice a week, and were instructed to avoid all other treatment. Post-intervention data collected included a clinical exam and another dorsaVI running analysis. Results: Data was analyzed including: pre and post-treatment initial peak acceleration, ground contact time, and ground reaction force. A paired t-test comparing pre and post mean kinetic changes demonstrated the following p values: initial peak acceleration p = .80, ground contact time p = .96, and ground reaction force p = .68. Conclusion: This study demonstrated that isolated MET treatment is not statistically significant for changing 3D kinetic running variable in subjects with low back pain. Clinical Implications: Recommend healthcare providers to use a multi-treatment approach for low back pain. Future research should include a control group and larger sample size.

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